Sorry to hear about this issue. Does anything in this article help: [[Quick fixes if your Firefox slows down]]? Some Windows 10 users are encountering severe performance problems with Firefox 57 related to accessibility services. Please see the reply from philipp in the following thread in case this bug is affecting your system: [https://support.mozilla.org/questions/1184485 Firefox 57 hangs up]. You might also test in Firefox's Safe Mode. In its Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, and some other advanced features to help you assess whether these are causing the problem. ''If Firefox is not running:'' Hold down the Shift key when starting Firefox. ''If Firefox is running:'' You can restart Firefox in Safe Mode using either: * "3-bar" menu button > "?" button > Restart with Add-ons Disabled * Help menu > Restart with Add-ons Disabled and OK the restart. ''Both scenarios:'' A small dialog should appear. Click "Start in Safe Mode" (''not'' Refresh). Any improvement?